Willemse, F.

would accompany the family into the mountains, sometimes on horseback. The
family still treasures many dear memories of these holidays.
At the end of a collection day, the catch of the day had to be prepared and labelled.
This meant that specimens belonging to the Ensifera had to be dissected,
their stomach and intestines removed. Subsequently, the body shape was restored
with cotton wool. As catches more often than not numbered in the hundreds
rather than the tens, the whole family participated. Upon return to The Netherlands,
the specimens were mounted and labelled, boxes constructed, and specimens
identified. All in all this would normally take about 3 months. This is quite a
short period, considering the amount of specimens brought back (2.500–6.000
per trip), the fact that labels were still printed by hand, and that the wooden boxes
were made by Fer himself (every year 30-50 boxes). As with the collecting,
Fer was assisted in many ways by family members.
Even in the relatively short span of Fer's life, fieldwork changed with the introduction
of various kinds of equipment like the bat detector (useful for locating species
producing a very soft or high-pitched calling song), a GPS device (rendering
coordinates), and of course sound recording equipment. At first, he was
somewhat sceptical about bioacoustics as a means to be used in taxon recognition.
As described by himself in the acknowledgements of his last paper on Chorthippus,
his views later changed:
"When I first met Otto von Helversen in 1986, he assured me that based on song
recording there was no doubt in his mind that C. vagans did occur in Greece
whereas based on the morphology alone it was not at all that obvious to me. As a
boy I found Chorthippus apricarius new to the Dutch fauna, based on its song
quite distinct from its morphologically syntopic look-alikes (C. Willemse 1940). It
was obvious that song characteristics, particularly among this group of grasshoppers,
constitute an easy and reliable means to establish the identity of certain
individuals or populations." (Zool. Meded. 83)
The first sound recordings were made was in 1986, and the last in 2004. Fer
recorded the songs of some 130 species, all of which have been handed over to
Baudewijn Odé.
Collection
The collection and library of his father C. Willemse were bequeathed, upon his
death in 1962, to the Natural History Museum in Maastricht. This museum focuses
on regional fauna, flora, and paleontology. It may seem odd to donate a collection
focused on South East Asian Orthoptera to a regional museum rather
than a larger national museum in Amsterdam or Leiden. However, C. Willemse
had very strong ties with the Museum in Maastricht and the "Natuurhistorisch
Genootschap in Limburg", which he chaired for 8 years. Before his father's collection
was moved to Maastricht, Fer Willemse made a small reference collection
of the European material, collected by himself, and some South East Asian taxa,
which were still unidentified or pending further studies.
The reference collection rapidly expanded to a significant collection that also included
type material. A separate paper will discuss the type material. The collection
was expanded in four ways.
110 [31.05.2010] ARTICULATA 25 (1)